MDMA (3,4-methylenedioxymethamphetamine) or 'Ecstasy' was scheduled as an illegal drug in 1986, but since then its recreational use has increased dramatically. This review covers 15 years of research into patterns of use, its acute psychological and physiological effects, and the long-term consequences of repeated use. MDMA is an indirect monoaminergic agonist, stimulating the release and inhibiting the reuptake of serotonin (5-HT) and, to a lesser extent, other neurotransmitters. Single doses of MDMA have been administered to human volunteers in double-blind placebo-controlled trials, although most findings are based upon recreational MDMA users. The 'massive' boost in neurotransmitter activity can generate intense feelings of elation and pleasure, also hyperactivity and hyperthermia. This psychophysiological arousal may be exacerbated by high ambient temperatures, overcrowding, prolonged dancing and other stimulant drugs. Occasionally the 'serotonin syndrome' reactions may prove fatal. In the days after Ecstasy use, around 80% of users report rebound depression and lethargy, due probably to monoaminergic depletion. Dosage escalation and chronic pharmacodynamic tolerance typically occur in regular users. Repeated doses of MDMA cause serotonergic neurotoxicity in laboratory animals, and there is extensive evidence for long-term neuropsychopharmacological damage in humans. Abstinent regular Ecstasy users often display reduced levels of 5-HT, 5-HIAA, tryptophan hydroxylase and serotonin transporter density; functional deficits in learning/memory, higher cognitive processing, sleep, appetite and psychiatric well-being, and, most paradoxically, 'loss of sexual interest/pleasure'. These psychobiological deficits are greatest in heavy Ecstasy users and may reflect serotonergic axonal loss in the higher brain regions, especially the frontal lobes, temporal lobes and hippocampus. These problems seem to remain long after the recreational use of Ecstasy has ceased, suggesting that the neuropharmacological damage may be permament. Copyright 2001 John Wiley& Sons, Ltd.

Three groups of young people (aged 19-30 years) were compared: 15 regular ecstasy users who had taken MDMA (3,4-methylenedioxymethamphetamine) on ten or more occasions; 15 novice ecstasy users who had taken MDMA on fewer than ten previous occasions; and 15 controls who had never taken MDMA. Each subject completed a cognitive test and mood scale battery four times: an initial drug-free baseline, at a Saturday night dance/club (on-drug), then 2 days later, and 7 days later. On the Saturday night, regular ecstasy users took an average of 1.80 MDMA tablets, novice users took 1.45 MDMA tablets, while controls mostly drank alcohol. The consumption of cannabis and cocaine at the club was similar across groups. All three groups reported positive moods at the dance club (on-drug), although there were borderline trends (P < 0.10) for less sadness/depression in the MDMA subgroups. However 2 days afterwards, the ecstasy users felt significantly more depressed, abnormal, unsociable, unpleasant, and less good tempered, than the controls. Cognitive performance on both tasks (verbal recall, visual scanning) was significantly reduced on-MDMA. Memory recall was also significantly impaired in drug-free MDMA users, with regular ecstasy users displaying the worst memory scores at every test session. This agrees with previous findings of memory impairments in drug-free ecstasy users. Animal data have shown that MDMA can generate long-term serotonergic neurodegeneration in various brain areas, including the hippocampus. The cognitive deficits in drug-free recreational ecstasy users, suggest that MDMA may also be neurotoxic in humans.

Smokers often report that cigarettes help relieve feelings of stress. However, the stress levels of adult smokers are slightly higher than those of nonsmokers, adolescent smokers report increasing levels of stress as they develop regular patterns of smoking, and smoking cessation leads to reduced stress. Far from acting as an aid for mood control, nicotine dependency seems to exacerbate stress. This is confirmed in the daily mood patterns described by smokers, with normal moods during smoking and worsening moods between cigarettes. Thus, the apparent relaxant effect of smoking only reflects the reversal of the tension and irritability that develop during nicotine depletion. Dependent smokers need nicotine to remain feeling normal. The message that tobacco use does not alleviate stress but actually increases it needs to be far more widely known. It could help those adult smokers who wish to quit and might prevent some schoolchildren from starting.

This review of chronic tolerance to MDMA (3,4-methylenedioxymetamphetamine) covers the empirical data on dosage escalation, reduced subjective efficacy and bingeing in recreational Ecstasy users. Novice users generally take a single Ecstasy tablet, regular users typically take 2-3 tablets, whereas the most experienced users may take 10-25 tablets in a single session. Reduced subjective efficacy following repeated usage is typically described, with many users subjectively reporting the development of tolerance. Intensive self-administration or bingeing is often noted by experienced users. This can comprise 'stacking' on several tablets together, and 'boosting' on successive doses over an extended period. Some experienced users snort Ecstasy powder nasally, whereas a small minority inject MDMA. Chronic tolerance and bingeing are statistically linked to higher rates of drug-related psychobiological problems. In terms of underlying mechanisms, neuroadaptive processes are certainly involved, but there is a paucity of evidence on hepatic and behavioural mechanisms. Further studies specifically designed to investigate chronic tolerance, involving low intermittent dose regimens, are required. Most animal research has involved intensive MDMA dosing regimens designed to engender serotonergic neurotoxicity, and this may comprise another underlying mechanism. If distal serotonin axon terminal loss was also developing in recreational users, it may help to explain why reducing subjective efficacy, dosage escalation and increasing psychobiological problems often develop in parallel. In conclusion, there is extensive evidence for chronic pharmacodynamic tolerance to recreational Ecstasy/MDMA, but the underlying mechanisms are currently unclear. Several traditional processes are probably involved, but one of the possible causes is a novel mechanism largely unique to the ring substituted amphetamine derivatives, namely serotonergic neurotoxicity.